CVE-2026-23433

/* * PoC Simulation for CVE-2026-23433 * This C code simulates the Null Pointer Dereference logic found in * the Linux kernel mpam_restore_mbwu_state function. * * Vulnerability Logic: * The function fails to initialize a pointer before passing it to a helper * function that attempts to write to it. */ #include <stdio.h> #include <stdlib.h> // Simulating the argument structure struct mbwu_arg { long *val; // Pointer that should be initialized but isn't }; // Simulating the __ris_msmon_read function behavior void simulated_read_func(struct mbwu_arg *arg) { printf("[Kernel] Attempting to read and update value...\n"); // The vulnerable line: dereferencing arg->val which is NULL *(arg->val) += 0x10; printf("[Kernel] Value updated.\n"); } // Simulating mpam_restore_mbwu_state void vulnerable_restore_state() { struct mbwu_arg args; // Vulnerability: args.val is not initialized (remains NULL) args.val = NULL; printf("[Vuln] Restoring MBWU state with uninitialized pointer...\n"); simulated_read_func(&args); } int main() { printf("PoC for CVE-2026-23433: Triggering Null Pointer Dereference\n"); vulnerable_restore_state(); return 0; }

{"cve": {"id": "CVE-2026-23433", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-04-03T16:16:24.777", "lastModified": "2026-04-23T20:59:54.533", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\narm_mpam: Fix null pointer dereference when restoring bandwidth counters\n\nWhen an MSC supporting memory bandwidth monitoring is brought offline and\nthen online, mpam_restore_mbwu_state() calls __ris_msmon_read() via ipi to\nrestore the configuration of the bandwidth counters. It doesn't care about\nthe value read, mbwu_arg.val, and doesn't set it leading to a null pointer\ndereference when __ris_msmon_read() adds to it. This results in a kernel\noops with a call trace such as:\n\nCall trace:\n__ris_msmon_read+0x19c/0x64c (P)\nmpam_restore_mbwu_state+0xa0/0xe8\nsmp_call_on_cpu_callback+0x1c/0x38\nprocess_one_work+0x154/0x4b4\nworker_thread+0x188/0x310\nkthread+0x11c/0x130\nret_from_fork+0x10/0x20\n\nProvide a local variable for val to avoid __ris_msmon_read() dereferencing\na null pointer when adding to val."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.19.1", "versionEndExcluding": "6.19.10", "matchCriteriaId": "D70DEFFE-AC47-4F3A-A2B2-2D67AB4CF3C8"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:6.19:-:*:*:*:*:*:*", "matchCriteriaId": "35C8A871-4971-433E-A046-FC9F7B7D190A"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*", "matchCriteriaId": "58A9FEFF-C040-420D-8F0A-BFDAAA1DF258"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*", "matchCriteriaId": "1D2315C0-D46F-4F85-9754-F9E5E11374A6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*", "matchCriteriaId": "512EE3A8-A590-4501-9A94-5D4B268D6138"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/4ad79c874e53ebb7fe3b8ae7ac6c858a2121f415", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/ac3e12bc195786d3d44d730b5b2259fd36191848", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}]}}